The present invention relates to a sequence controller system for regenerating a water treatment plant having a plurality of treatment units for treatment of water flowing therethrough. A water treatment unit may use a chemical process for removing hard salts from hard water by the interchange of cations when the hard water is passed through a resing contained in a treatment tank. Also, water treatment units may use a chemical process for the deionization of salt water to obtain sufficiently pure water for industrial uses. After a preriod of time of extended use the resin used in the chemical process begins to deplete and the water flowing from the water treatment unit begins to deteriorate. At such time depleted resin must be regenerated by passing a regenerating solution through the water treatment unit to restore the resin to its original condition for further service. A water treatment unit may also be a filter which requires periodic backwashing and rinsing.
In the prior art there are problems with the regeneration of a plurality of water treatment units when two or more of the water treatment units are simultaneously ready for regeneration. When two or more water treatment units are simultaneously regenerated the capacity of the remaining water treatment units in service is appreciably diminished so that the treated water flowing therefrom may be unsatisfactory for service. Another problem is that the regeneration of two or more units simultaneously may result in the resin in each of the water treatment units to be improperly regenerated.
It is an object of the present invention to permit the regeneration of only a single water treatment unit at a time by the use of an interlock and a priority circuit utilizing synchronized timing signals to determine the interlock status of each water treatment unit and to establish regenerating priorities between the individual water treatment units in the water treatment plant.
The exact nature of the present invention as well as other objects and advantages thereof will be apparent by consideration of the following specification related to the annexed drawings: